Ratchet mechanism for watch-movements.



H. M. GEOFF RATGHET MECHANISM FOR WATCH MOVEMENTS, 11111111111111111111111111 0.

971,500. Patented Sept 27, 1910.

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UNITED STATES PATENT OFFICE.

HOWARD METZLER GEOFF, OF WALTHAM, MASSACHUSETTS, ASSIG-NOR TO THE KEY- STONE WATCH CASE COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A CORPORA- 'IION OF PENNSYLVANIA.

RATCHET MECHANISM FOR- WATCH-MOVEMENTS.

Specification of Letters Patent.

Patented Sept. 27, 1910.

To all whom it may concern:

Be it known that I, HOWARD M. Grow, a citizen of the United States, and resident of Vifaltham, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Ratchet Mechanisms for atch-Movements, of which the following is a specification.

My invention relates more particularly to the construction of the clicks or detents which are used in connection with the ratchet wheels of watch movements for the purpose of locking said wheels against backward movement, and is intended to provide a simple and effective click which will be inexpensive in construction and will also operate in such manner that after the ratchet wheel has been turned in the proper direction to wind the watch a limited backward movement of said wheel under the influence of the main spring will be provided for, whereby the main spring will be relaxed slightly after havin been wound up and it will consequentfy be impossible to leave it so tightly wound as to cause it to bind and thus become inoperative for its intended purpose.

A ratchet mechanism embodying my invention, as preferably constructed, is illustrated in the accompanying drawing, in which:

Figure 1 is a plan view of a portion of a watch movement, showing the detent in position to slip over the teeth of the ratchet wheel; Fig. 2 is a similar view showing the detent in position to lock the ratchet wheel against backward movement; Fig. 3 is a plan view of the detent, detached; and Fig. 4 is a transverse section on the line l l in Fig. 1.

In the drawings, 2 indicates the ratchet wheel of a watch movement and 3 indicates the supporting plate carrying the stud & on which the wheel 2 is journaled in the usual manner. Adjacent to the periphery of the wheel 2 is located a tooth-engaging arm 5 which is mounted to oscillate in the plane of said wheel on a pivot 6 carried by the plate 3, the oscillating movement of said arm in one direction being limited by a fixed stop and in the other direction by a spring stop. In the particular construction illustrated one of the elements of the spring stop just re ferred to consists of an arm 7 connected to the arm 5 by a spring 8, which spring is substantially circular in shape and is fitted to turn on the pivot 6, the arms 5 and 7 being thus adapted to oscillate in unison to a limited extent, and in connection with the arms 5 and 7 fixed abutments are provided for limiting the oscillation of said arms by engaging one or the other of them according to the direction of their movement. By preference, in order that the thickness of the watch movement may not be increased, said fixed abutments are formed by the walls of a recess 10 in which the arms 5 and 7 oscillate, the upper surfaces of said arms being iiush with the surface of the plate 3 as shown in Fig. 4. For the same reason the spring portion 8 is reduced in thickness to provide a recess adapted to receive the head of the pivot t3.

The parts 5, 6, 7, 8 and 10 are so proportioned and arranged with reference to the wheel 2 that when said parts are in the positlon shown in Fig. l the stop arm 7 is in contact with the adjacent wall of the recess 10, while the tooth-engaging arm 5 slants forward from the pivot 6, with reference to the direction of movement of the adjacent teeth 9 while the watch is being wound, and bears at its free end upon one of said teeth. During the rotation of the wheel 2 in winding the watch the spring 8 permits the arm 5 to ride over the teeth 9 in the usual manner, but as soon as winding of the watch is stopped and the wheel 2 is released the reaction of the main spring causes that tooth which is next in advance of the free end of the arm 5 to engage the latter and move it backward until it brings up against the adjacent wall of the recess 10, in which position said arm extends substantially in a radial direction with respect to the wheel 2 and has its free end located between two of the teeth 9, with the result that said wheel is positively locked against further backward movement, as shown in Fig. 2. The backward movement of the wheel 2 which has already taken place, however, is sufficient to relax the main spring slightly and thus prevent it from becoming bound in case it has been wound up as tightly as possible.

In order to minimize the cost of construction of the click mechanism above described, the recess 10 which receives the arms 5 and 7 and their pivot is preferably composed of intersecting circular portions, of which the portion which contains said arms also intersects the eircular recess which receives the ratchet wheel 2, such recesses being readily its free end with the teeth of said wheel, and

formed by simple boring operations. such case the outer edges of the arms 5 and 7 are also formed on curved lines conforming to the periphery of the recess in which said arms are located. The detent may readily be made from a single piece of spring steel by first stamping out a blank having the external contour of the detent, then reducing the thickness of its pivotal end by an amount equal to the thickness of the head of the pivot, then boring a hole to receive said pivot, leaving the right amount of metal to serve as a spring, and finally cutting away the metal between the arms 5 and 7.

The retrogade movement permitted to the ratchet wheel may be given any desired ex tent by constructing the arm 5 of appropriate length, and the various details of construction and proportion may be otherwise modified without departing from my invention, as will be evident.

I claim as my invention:

1. In a watch movement, the combination with the ratchet wheel of a detent arm mounted to oscillate in engagement with the teeth of said wheel, a fixed stop arranged to engage and limit the backward movement of said detent arm, a stop arm having a spring connection with the detent arm and oscillating therewith, and a fixed stop arranged to limit the forward movement of said stop arm.

2. In a watch movement, the combination with the ratchet wheel of a detent comprising two arms connected by a spring and mounted to oscillate on a pivotal axis, the rear arm being in constant engagement with the teeth of said wheel and serving as a detent arm and the forward arm being out of engagement with said teeth and serving as a stop arm, and fixed stops arranged to limit the backward and forward movements of said arms respectively.

3. In a watch movement, the combination with the ratchet wheel of two rigid arms connected by a substantially circular spring, a fixed pivot forming a bearing for said spring and serving as a pivotal axis for said arms, the rear arm being engaged at In fixed stops to limit the forward and backward movements of the respective arms.

4. In a watch movement, the combination with the ratchet wheel of a one-piece oscillating detent comprising a detent arm and a stop arm connected by a substantially circular spring, a fixed pivot passing through and forminga bearing for said spring, and fixed stops arranged to limit the backward movement of the detent arm and the forward movement of the stop arm respectively.

5. In a watch movement, the combination of the ratchet wheel and the plate on which the same is journaled, said plate being pro vided with intersecting circular recesses, a detent arm and a stop arm located in the recess adjacent to the ratchet wheel and adapted to oscillate therein, the walls of said recess serving as stops to limit the backward movement of the detent arm and the forward movement of the stop arm, a substantially circular spring located in the other recess and connecting said arms, and a pivot pin passing through said spring and forming a bearing therefor.

6. In a watch movement, the combination of the ratchet wheel and the plate on which the same is journaled, said plate being provided with intersecting circular recesses, a detent arm and a stop arm located in the recess adjacent to the ratchet wheel and adapted to oscillate therein, the walls of said recess serving as stops to limit the backward movement of the detent arm and the forward movement of the stop arm, a substantially circular spring located in the other recess and connecting said arms, and a pivot pin passing through said spring and forming a bearing therefor, said spring being cut away on its outer surface to receive the head of said pivot pin.

In testimony whereof, I have hereunto subscribed my name this 31st day of January, 1910.

HOIVARD METZLER GEOFF. lVitnesses IV. H. EBELHARE, W. B. MEHL. 

